As an additional note, the reprogrammability of the F1 is awesome. There I was, with the F1 and two D3's inside a beaker of water, and the beaker was in the pressure chamber, to simulate underwater pressure conditions. After numerous pressure tests in the range of 10-66m, I wasn't happy with the F1 accuracy (at the time it was 1%). So I decided to fine tune the calibration coefficients. I removed the F1 from the water, dried it off, adjusted the coefficients in the C program, recompiled the program, and the downloaded the new software in the F1. Within less than 3-4 minutes, the F1 was underwater again, running the new software, this time with 0.35% accuracy. Unbelievable to be able to dry off a wet gauge, re-load the entire software, then put it back in the water just minutes later!!
Inside the dark pressure chamber, everything glowed yellow from the yellow display on the F1. In those dark conditions, of course, the D3's could not be read at all.
Example from the last two pressure tests:
#1 Pressurization depth 43.33m
F1 reads 43.3m (error = 0.07%)
D3 #1 reads 43.5m (error = 0.40%)
D3 #2 reads 43.6m (error = 0.62%)
#2 Pressurization depth 64.80m
F1 reads 65.0m (error = 0.30%)
D3 #1 reads 65.5m (error = 1.07%)
D3 #2 reads 65.4m (error = 0.92%)
And this is still with only a two point calibration method!! Production F1's will use a four to six point calibration method, dramatically increasing the accuracy even beyond the 0.2m or +/-0.35%.
However, here is something which is really disturbing. The D3's measured time quite accurately until the dive time went over 5 minutes. Suddenly the time accuracy decreased dramatically.
Here are the results from a test of the D3's, IN THE SAME PRESSURE CHAMBER, on the SAME simulated dive:
Pressurization depth 64.59m
D3 #1: 65.4m, time = 8'13"
D3 #2: 65.2m, time = 7'29"
[ time difference between the two D3's: 44 seconds! ]
Pressurization depth 65.14m
Water temperature exactly 13.5 deg C
D3 #1: 65.9m, time = 9'25", T=13 deg C
D3 #2: 66.0m, time = 10'11", T=12 deg C
[ time difference between the two D3's: 46 seconds! ]
How is it possible that the D3's show such different dive times??
Inside the dark pressure chamber, everything glowed yellow from the yellow display on the F1. In those dark conditions, of course, the D3's could not be read at all.
Example from the last two pressure tests:
#1 Pressurization depth 43.33m
F1 reads 43.3m (error = 0.07%)
D3 #1 reads 43.5m (error = 0.40%)
D3 #2 reads 43.6m (error = 0.62%)
#2 Pressurization depth 64.80m
F1 reads 65.0m (error = 0.30%)
D3 #1 reads 65.5m (error = 1.07%)
D3 #2 reads 65.4m (error = 0.92%)
And this is still with only a two point calibration method!! Production F1's will use a four to six point calibration method, dramatically increasing the accuracy even beyond the 0.2m or +/-0.35%.
However, here is something which is really disturbing. The D3's measured time quite accurately until the dive time went over 5 minutes. Suddenly the time accuracy decreased dramatically.
Here are the results from a test of the D3's, IN THE SAME PRESSURE CHAMBER, on the SAME simulated dive:
Pressurization depth 64.59m
D3 #1: 65.4m, time = 8'13"
D3 #2: 65.2m, time = 7'29"
[ time difference between the two D3's: 44 seconds! ]
Pressurization depth 65.14m
Water temperature exactly 13.5 deg C
D3 #1: 65.9m, time = 9'25", T=13 deg C
D3 #2: 66.0m, time = 10'11", T=12 deg C
[ time difference between the two D3's: 46 seconds! ]
How is it possible that the D3's show such different dive times??